The objective of the proposed project is to obtain an understanding of the structure and function of membrane associated proteins which are involved in mediating the uptake of amino acids and cholesterol in mammalian cells. Studies will be carried out to determine the structure and function of gamma-glutamyl transpeptidase and low density lipoprotein (LDL) receptor since these proteins are localized in the plasma membrane of a number of mammalian cells and are implicated to play an important role in the transport of amino acids and cholesterol (via LDL pathway) respectively. Morever, structure and transport functions of these proteins are relatively little understood. We propose to investigate the structure and function of gamma-glutamyl transpeptidase using liposomal model system. Studies show that gamma-glutamyl transpeptidase mediates the transport of amino acids in liposomal system and thus supports the functional role of this enzyme in transport of amino acids in natural membranes. The structure of LDL receptor in cells will be established using chemical approach. These studies would provide not only an insight into the molecular aspects of abnormality in LDL receptor defect observed in familial hypercholesterolemic individuals but also an impetus for the design of drugs to ameliorate or abolish the clinical manifestations of hypercholesterolemia.